Fullmer,2 in 1958, demonstrated a connective tissue fiber that differed in its staining properties and histochemical characteristics from all those previously described. Due to its resistance to acid hydrolysis, it was designated the oxytalan fiber. After peracetic acid oxidation, the oxytalan fiber reacts with aldehyde fuchsin and stains deep purple, while the collagen fibers remain unstained. The oxytalan fiber does not react to the usual elastic tissue stains or to procedures generally used for the identification of collagen and reticulin fibers.3

Oxytalan fibers so far have been identified in structures particularly subjected to mechanical stress,2 namely, tendons, ligaments, adventitia of blood vessels, epineurium, perineurium, and the connective tissue sheaths that surround the skin appendages. They are not found in the ordinary connective tissue of normal dermis, granulation tissue, or in the fibrous stroma of the viscera. The oxytalan fiber has been shown to be a component of